Protectors for electric circuits



Jan. 14, 1964 J. c. LEBENS PROTECTORS FOR ELECTRIC CIRCUITS Filed Aug. 24, 195

e K m a N r Z A .7 N5 5 L a c F g M M J y m a 0 0 a Z 2 8 mg :c FE 4 6 w p v Ll lhflfi 7 a a Q 2 6 m w W F b United States Patent Ofiice 3,118,035 Patented Jan. 14, 1964 3,118,035 PROTECTORS FOR ELECTRIC CIRCUITS John C. Lebens, University City, Mo., assignor t McGraw-Edison Company, Elgin, Ill., a corporation of Delaware Filed Aug. 24, 1959, Ser. No. 835,589 7 Claims. (Cl. 200-419) This invention relates to improvements in protectors for electric circuits. More particularly, this invention relates to improvements in adapters for the terminals of electric fuses.

It is therefore an object of the present invention to provide an improved adapter for the terminals of electric fuses.

It is frequently desirable to replace the electric fuses in a fuse box or on a panel board with electric fuses having a smaller rating; and, in many instances, the fuses having the smaller rating have physical dimensions that are smaller than the physical dimensions of the fuses they replace. Where this is the case; the fuses having the smaller rating may not, and usually will not, properly fit the fuse clips in the fuse box or on the panel board. To enable the fuses, which have the smaller physical dimensions, to be disposed in intimate electrical connection with the fuse clips, it is customary to provide adapters which can be mounted on the terminals of the fuses, which have the smaller physical dimensions; and those adapters will snugly fit in the fuse clips and thereby intimately electrically connect those fuses with those fuse clips. The present invention provides an adapter for electric fuses; and that adapter is simple, inexpensive and effective.

The adapter provided by the present invention has a body portion that is dimensioned to fit within, and to make good electrical contact with, a fuse clip; and that adapter has a recess within which the terminal of a fuse can fit. That recess is bounded, at least in part, by bendable walls or arms that can be pressed into, and held in, intimate engagement with the terminal of the fuse; and that engagement provides the required good electrical contact between the terminal and the adapter. It is, therefore, an object of the present invention to provide an adapter which has a body portion that can fit within, and make good electrical contact with, a fuse clip and which has a recess that is bounded, at least in part, by bendable walls or arms and that can accommodate the terminal of a fuse.

The adapter provided by the present invention will preferably be made of a metal having a low resistivity, and such a metal does not have a high degree of resilience. Moreover, the resilience of such a metal decreases rapidly as the temperature of that metal rises to the levels at which fusible links of comparable metals blow. Consequently, the bendable walls of the recess of the adapter provided by the present invention can not, in and of themselves, provide and maintain a high degree of electrical contact between the adapter and the fuse terminal disposed within the recess of that adapter. The present invention provides and maintains the desired high degree of electrical contact between that adapter and that fuse terminal by using a clamp of steel or some comparable metal to hold the bendable walls of the recess of that adapter in intimate engagement with that fuse terminal. Such a clamp has a high degree of resilience, and it will maintain that high degree of resilience throughout the entire range of temperatures to which it will be subjected during its use with the adapter. It is therefore an object of the present invention to provide an adapter, made from a metal of low resistivity, with a clamp that is made of a metal which has a high degree of resilience and which will maintain that high degree of resilience throughout the entire range of temperatures to which it will be subjected during its use with the adapter.

The bendable walls or arms which, at least in part, define the recess in the adapter have the confronting faces thereof provided with configurations that are generally complementary to those portions of the fuse terminal which those confronting faces will engage. Thus, where the confronting faces of the bendable walls or arms of the adapter will engage the edges of a knife blade fuse terminal, those confronting faces will be made generally concave. As a result, the confronting faces of the bendable walls or arms of the adapter will be able to apply forces to the terminal, interposed between them, that will resist accidental separation of that terminal from that adapter. It is therefore an object of the present inven tion to provide the confronting faces, of the bendable walls or arms that define the recess of the adapter, with configurations that are complementary to those portions of the fuse terminal that will be engaged by those confronting faces.

The recess in the adapter provided by the present inven tion opens to one end of that adapter. As a result, that recess is U-shaped in configuration. The clamp, that applies the forces that will hold the bendable walls or arms of the adapter in intimate engagement with the fuse terminal, will be set adjacent that one end of the adapter; and, as a result, that clamp will not interfere with the insertion and removal of the adapter into and out of the fuse clip.

Other and further objects and advantages of the present invention should become apparent from an examination of the drawing and accompanying description.

In the drawing and accompanying description, two preferred embodiments of the present invention are shown and described, but it is to be understood that the drawing and accompanying description are for the purpose of illustration only and do not limit the invention and that the invention will be defined by the appended claims.

In the drawing,

FIG. 1 is a plan view of a knife blade cartridge fuse which is equipped with two adapters that are made in accordance with the principles and teachings of the present invention,

FIG. 2 is a sectional view, on an enlarged scale, through one of the adapters and one of the fuse terminals shown in FIG. 1, and it is taken along the plane indicated by the line 22 in FIG. 1,

FIG. 3 is a plan view, on the scale of FIG. 2, showing one of the adapters of FIG. 1,

FIG. 4 is a sectional view, on the scale of FIG. 2, and it is taken along the plane indicated by the line 44 in FIG. 1,

FIG. 5 is a sectional view, on a still larger scale, of one of the bendable walls or arms of the adapter of FIG.

a a 3, and it is taken along the plane indicated by the line --5 in FIG. 3, and

FIG. 6 is a plan view of another adapter that is made in accordance with the principles and teachings of the present invention.

Referring to the drawing in detail, the numeral 10 generally denotes a fuse which has knife blade terminals 12. Those terminals are designed and dimensioned to fit fuse clips of a certain size; but where they are equipped with the adapters provided by the present invention, those terminals can be held securely by fuse clips that are larger and that are spaced further apart.

The numeral 14 generally denotes one form of adapter that is made in accordance with the principles and teach ings of the present invention; and that adapter has a body portion 16. A recess is defined at one end of that adapter by walls or arms 17; and those walls or arms provide a generally U-shaped configuration for that adapter. Each of the walls or arms 17 is provided with ridges 18 at the upper and lower surfaces thereof, and those ridges coact with the confronting faces of the walls or arms 17 to provide a generally concave configuration for those confronting faces; all as shown by FIG. 5.

The normal distances between the confronting faces of the walls or arms 17 of the adapters 14 are slightly greater than the widths of the terminals 12 of the fuse 10; and, as a result, the terminals 12 of the fuse 1G readily telescope within the recesses defined by those walls or arms. The walls or arms 17 are not limp but, instead, are sturdy and are relatively stiff. However, those walls or arms can be bent toward each other to force the confronting faces thereof into intimate engagement with the edges of the terminals 12 of the fuse 10. The walls or arms 17 of any one of the adapters 14 will be bent toward each other by a clamp which includes J-shaped bars 2%, bolt 21, and nut 22. The bars 2-1), the bolt 21, and the nut 22 will be made of steel or some other metal which is strong, which has a high degree of resilience, and which can maintain its strength and its high degree of resilience at temperatures including and even exceeding the range of temperatures attained by the fusible links of electric fuses when they blow.

The concave portions of the J-shaped bars 20 have configurations that are complementary to the outer faces of the walls or arms 17; all as shown by FIG. 2. As a result, those concave portions snugly engage the outer faces of those walls or arms and prevent accidental separation of those bars from those walls or arms. The stems of the J-shaped bars 26 have generally L-shaped upper ends, and those L-shaped ends have openings 23 extending through them. Those openings accommodate the bolt 21, and the nut 22 is threaded onto the end of that bolt. When the bolt 21 is tightened relative to the nut 22, the J-shaped bars 245 will be drawn toward each other. As a result, the concave portions at the lower ends of the stems of those bars will pull the end of the walls or arms 17 into intimate engagement with the edges of the fuse terminals 12.

In the event the fuse 10 is recurrently subjected to overloads that do not cause that fuse to blow but that do cause that fuse and its terminals 12 to become heated, those terminals will expand. That expansion will force the walls or arms 17 of the adapters 14 to move outwardly. Such movement will be accommodated by slight bending of the L-shaped portions at the upper ends of the stems of the J-shaped bars 20; those L-shaped portions offsetting the holes for the bolts 21 from the stems of those bars so slight bends in those L-shaped portions will accommodate appreciable outward movements of the walls or arms 17. After the fuse 10 and its terminals 12 have cooled, the L-shaped portions at the upper end of the J-shaped bars 20 will return to their normal positions and continue to hold the walls or arms 17 in intimate engagement with the edges of the terminals 12. In this way, the required intimacy of engagement between the walls or arms 17 of the adapters 14 and the edges of the terminals 12 is maintained throughout the entire temperature range to which the adapters 14 will be subjected while clamped to those terminals.

The body portions 16 of the adapters 14 have widths and thicknesses that correspond to the widths and thicknesses of the terminals of the large fuse which is to be replaced by the fuse 19. As a result, those body portions can receive and withstand the forces and pressures which will be applied to them by the fuse clips; and those body portions will thus enable the adapters 14 to assure a full electrical connection between the fuse 10 and the fuse clips.

The numeral 30, in FIG. 6, generally denotes another adapter that is made in accordance with the principles and teachings of the present invention. That adapter has a body portion 32, walls or arms 34, and a slot 38. The walls or arms 34 are provided, at their upper and lower surfaces, with ridges 36 comparable to the ridges 18 of FIGS. 1-5. The walls or arms 34 are comparable to, but are wider than, the walls or arms 17 of the adapters 14; and, therefore, the adapter 30 can accommodate a smaller fuse terminal than can either of the adapters 14.

The fact that the walls or arms 34 are wider than the walls or arms 17 means that those walls or arms are stiffer than the walls or arms 17. As a result, the walls or arms 34 are not as bendable as are the walls or arms 17. However, the slot 38 compensates for the extra stiffness of the walls or arms 34 and permits a clamp to force the confronting faces of those walls or arms into intimate engagement with the edges of a fuse terminal interposed between those walls or arms. That clamp has the J-shaped bars 20, the bolt 21, and the nut 22 of the clamp shown in FIGS. 1 and 2.

By proper dimensioning of the walls or arms of the adapters, the present invention makes it possible to provide a range of adapters that can hold a range of fuses in one set of fuse clips. Thus, by proper dimensioning of the walls or arms of the adapters, it is possible to hold a one hundred ampere fuse, a two hundred ampere fuse or a four hundred ampere fuse in fuse clips intended to accommodate a six hundred ampere fuse.

In any adapter used with electric fuses, there must be a yielding and a subsequent restoration; because without the yielding, the thermal expansion of the terminal would break the adapter, and without the subsequent restora tion, the adapter would be unable to maintain its tight engagement with the fuse terminal as that fuse terminal cooled. The present invention provides the requisite yielding and subsequent restoration by making the arms of the adapter bendable and by holding those arms in engagement with the terminal by means of a clamp whose strength and resilience are substantially unaffected by the temperatures to which that clamp will be subjected while assembled with the adapter.

Whereas the drawing and accompanying description have shown and described two preferred embodiments of the present invention it should be apparent to those skilled in the art that various changes may be made in the form of the invention without affecting the scope thereof.

What I claim is:

1. An adapter, for one of the knife blade terminals of a knife blade cartridge enclosed electric fuse, which makes it possible to mount said one terminal of said fuse in a fuse clip which accommodates a knife blade terminal of a larger knife blade cartridge enclosed electric fuse and that has a flat body portion and that has arms projecting from one end of said body portion, and a clamp that holds said arms in intimate electrical engagement with said one terminal, said body portion being wider and thicker than said one terminal whereby said body portion can intimately engage said fuse clip, said arms being elongated and having lengths approximating the length of said one terminal, said arms being thicker than said one terminal and having ridges on the upper and lower faces thereof that extend longitudinally of said arms and that render the confronting faces of said arms generally concave, said arms coacting with said one end of said body portion to provide a generally U-shaped configuration for said adapter and said arms and said one end of said body portion being dimensioned to define a recess that can accommodate said one terminal, said confronting faces of said arms of said adapter normally being spaced apart a distance greater than the distance between the edges of said one terminal but being bendable into intimate electrical engagement with said edges of said one terminal by said clamp, said clamp including J-shaped bars and a bolt and nut, said J-shaped bars having concave portions at the lower ends of the stems thereof which can engage the outer faces of said arms of said adapter and having L-shaped portions at the upper ends of the stems thereof, said L-shaped portions having openings therein that accommodate said bolt, said bolt being rotatable relative to said nut to pull said bars toward each other and thereby bend said arms into intimate electrical engagement with said edges of said one terminal, said adapter being made of copper, said clamp being made of steel, said body portion having a slot therein that is contiguous with said recess defined by said body portion and said arms, said slot facilitating the bending of said arms into intimate electrical engagement with said one terminal, said clamp yielding to accommodate expansion of said one terminal and of said arms of said adapter as said one terminal and said adapter become heated but subsequently restoring itself as said one terminal and said adapter cool and thereby maintaining said intimate electrical engagement between said arms and said one terminal, said clamp being disposed adjacent the free ends of said arms.

2. An adapter, for one of the terminals of a cartridge enclosed electric fuse, which makes it possible to mount said one terminal of said fuse in a fuse clip which accommodates a terminal of a cartridge enclosed electric fuse of greater size and that has a fiat body portion and that has arms projecting from one end of said body portion, and a clamp that holds said arms in intimate electrical engagement with said one terminal, said body portion being wider and thicker than said one terminal whereby said body portion can intimately engage said fuse clip, said arms being elongated, said arms having ridges on the upper and lower faces thereof that extend longitudinally of said arms and that render the confronting faces of said arms generally concave, said arms coacting with said one end of said body portion to provide a generally U-shaped configuration for said adapter and said arms and said one end of said body portion being dimensioned to define a recess that can accommodate said one terminal, said confronting faces of said arms of said adapter normally being spaced apart a distance greater than the distance between the edges of said one terminal but being bendable into intimate electrical engagement with said edges of said one terminal by said clamp, said clamp including J-shaped bars and a bolt, said J-shaped bars having concave portions at the lower ends of the stems thereof which can engage the outer faces of said arms of said adapter, said bolt being rotatable to pull said bars toward each other and thereby bend said arms into intimate electrical engagement with said edges of said one terminal, said clamp yielding to accommodate expansion of said one terminal and of said arms of said adapter as said one terminal and said adapter become heated but subsequently restoring itself as said one terminal and said adapter cool and thereby maintaining said intimate electrical engagement between said arms and said one terminal.

3. An adapter, for one of the terminals of an electric fuse, which makes it possible to mount said one terminal of said fuse in a fuse holder which accommodates a larger fuse terminal and that has a body portion and that has arms projecting from said body portion, and a clamp that holds said arms in intimate electrical engagement with said one terminal, said body portion being adapted to intimately engage said fuse holder, said arms being elongated, said arms coacting with said one end of said body portion to provide a generally U-shaped configuration for said adapter and said arms and said one end of said body portion being dimensioned to define a recess that can accommodate said one terminal, said clamp yielding to accommodate expansion of said one terminal and of said arms of said adapter as said one terminal and said adapter become heated but subsequently restoring itself as said one terminal and said adapter cool and thereby maintaining said intimate electrical engagement between said arms and said one terminal.

4. An adapter, for one of the terminals of an electric fuse, which makes it possible to mount said one terminal of said fuse in a fuse holder which accommodates a larger fuse terminal and that has a body portion and that has arms, and a clamp that holds said arms in intimate electrical engagement with said one terminal, said arms normally being spaced apart a distance that enables said one terminal to be readily interposed between said arms, said clamp being adapted to bend said arms into intimate electrical engagement with said one terminal.

5. An adapter, for one of the terminals of an electric fuse, which can be secured to and carried by said one terminal of said fuse and which makes it possible to mount said one terminal of said fuse in a fuse holder which is dimensioned to accommodate a larger fuse terminal and which is too large to be intimately engaged by said one terminal of said fuse, and that has a holder-engaging portion which is dimensioned to intimately engage said fuse holder for said larger fuse terminal and that has bendable portions that project from said holder-engaging portion and that at least in part define a recess, and a clamp engaging said bendable portions of said adapter, said recess being dimensioned to accommodate at least a part of said one terminal, said clamp being adapted to bend said bendable portions into intimate electrical engagement with said one terminal.

6. An adapter, for one of the terminals of an electric fuse, which can be secured to and carried by said one terminal of said fuse and which makes it possible to mount said one terminal of said fuse in a fuse holder which is dimensioned to accommodate a larger fuse terminal and which is too large to be intimately engaged by said one terminal of said fuse, and that has a holder-engaging portion which is dimensioned to intimately engage said fuse holder for said larger fuse terminal and that has bendable portions that project from said holder-engaging portion and that at least in part define a recess, and a clamp engaging said bendable portion of said adapter, said recess being dimensioned to accommodate at least a part of said one terminal, said clamp being adapted to bend said bendable portions into intimate electrical engagement with said one terminal, said clamp being made of a metal having a greater strength but a smaller thermal coefiicient of expansion than the metal of which said adapter is made, whereby said clamp can yield to accommodate thermal expansion of said terminal and of said adapter but can restore itself, when said terminal and said adapter cool, to maintain said intimate electrical engagement.

7. An adapter, for one of the terminals of an electric fuse, which can be secured to and carried by said one terminal of said fuse and which makes it possible to mount said one terminal of said fuse in a fuse holder which is dimensioned to accommodate a larger fuse terminal and which is too large to be intimately engaged by said one terminal of said fuse, and that has a holder-engaging portion which is dimensioned to intimately engage said fuse holder for said larger fuse terminal and that has bendable portions that project from said holder-engaging portion and that at least in part define a recess, and a clamp engaging said bendable portions of said adapter, said recess being dimensioned to accommodate at least a part of said one terminal, said clamp being adapted to bend said bendable portions into intimate electrical engagement with said one terminal, said adapter having a slot in said holderengaging portion, said slot being intermediate said bendable portions and being generally axially-directed of said one terminal Whenever said adapter is secured to and car ried by said one terminal, said slot facilitating the forcing of said bendable portions into intimate electrical engagement with said one terminal.

References Cited in the file of this patent UNITED STATES PATENTS 1,245,151 Conrad Nov. 6, 1917 Baker Jan. 31, Hynes Apr. 25, La Mar Mar. 21, Frank Apr. 3, Schwendt et a1 Nov. 10, Hain Nov. 7, Keller et al Nov. 11, Fortney Mar. 10, Wengen et a1. Oct. 28, Barrett et a1 Dec. 16, 

5. AN ADAPTER, FOR ONE OF THE TERMINALS OF AN ELECTRIC FUSE, WHICH CAN BE SECURED TO AND CARRIED BY SAID ONE TERMINAL OF SAID FUSE AND WHICH MAKES IT POSSIBLE TO MOUNT SAID ONE TERMINAL OF SAID FUSE IN A FUSE HOLDER WHICH IS DIMENSIONED TO ACCOMMODATE A LARGER FUSE TERMINAL AND WHICH IS TOO LARGE TO BE INTIMATELY ENGAGED BY SAID ONE TERMINAL OF SAID FUSE, AND THAT HAS A HOLDER-ENGAGING PORTION WHICH IS DIMENSIONED TO INTIMATELY ENGAGE SAID FUSE HOLDER FOR SAID LARGER FUSE TERMINAL AND THAT HAS BENDABLE PORTIONS THAT PROJECT FROM SAID HOLDER-ENGAGING POR- 